i have been looking at getting some Edelbrock TES headers for my 5.3, they aren't exactly long tube but they aren't shorties either. all the dynos off of them have put up good numbers, around 15-20hp gains. most of what is out there for your 6.0 is shorties from what i've seen. if you get TES or long tubes, there's most likely going to be some cutting/welding required for installation.